1. Field of the Invention
The present invention relates to an apparatus for preventing the unauthorized use of an electrical device.
2. Description of the Prior Art
The hazards attendant with the unauthorized or accidental use of hazardous electrical equipment have lead to the promulgation of Occupational Safety and Health Administration Regulations 29 C.F.R. Part 1910, Oct. 31, 1989. In general such regulations are designed to protect employees from the release of potentially hazardous energy while maintenance and/or servicing activities are being preformed. These regulations require employers to establish a program and to utilize procedures for affixing appropriate use prevention, or "lockout", apparatus on a piece of electrical equipment. The lockout apparatus serves to prevent the unauthorized or accidental operation, energization or start-up of the equipment. The lockout apparatus must be removed or disabled before operation of the electrical equipment can occur.
Presently, at least three classes of apparatus for preventing the unauthorized use of an electrical device are known in the art. One class of lockout apparatus is operable to prevent the connection of the power plug of the electrical device to an energy source. A second class of lockout apparatus is attachable to the actuating lever of a switch on the electrical device and, when so attached, is operable to impede the manipulation of the switch. A third class of lockout apparatus takes the form of a removable component of an switch which, if absent, prevents actuation of the electrical device.
Typically lockout apparatus of the first mentioned class is arranged so as to interact with the power blades of the power plug of the electrical device. When the use prevention apparatus is secured to the plug the insertion of the plug into a power outlet is prevented, thus precluding the use of the electrical device. Exemplary of such prior art apparatus are those disclosed in U.S. Pat. No. 3,543,544 (Efston), U.S. Pat. No. 2,654,073 (Katz), U.S. Pat. No. 4,025,140 (Matys), U.S. Pat. No. 4,445,738 (Wiencke), U.S. Pat. No. 4,566,297 (Hawley), U.S. Pat. No. 2,664,734 (McEneaney), and U.S. Pat. No. 2,733,416 (Evalt).
Lockout apparatus as exemplified by the above-mentioned patents usually include a body member, or block, having a passage formed therein which accepts one or both of the blades of the electrical plug. A gripping arrangement is disposed within the interior of the block. The gripping arrangement either acts against a surface on one or both of the blades and/or engages a feature thereon, such as an opening formed in a blade. This class of lockout apparatus includes a lock-key arrangement which would comply with the OSHA regulations. In general such lockout apparatus as exemplified by the referenced patents are generally mechanically complex in structure.
The second of the above-mentioned class of lockout apparatus is adapted for use with the operating lever found on circuit breaking equipment. Manipulation of the lever along an arcuate path changes the state of the switch from the "off" to the "on" position, and return. One example of such lockout apparatus is a clip sold by Crouse-Hinds Company, a division of Cooper Industries, Inc., Syracuse, N.Y. The clip is generally spoon-like in configuration having an elongated handle and a hollowed portion that is specifically sized to accept the operating lever of a circuit breaker available from a predetermined manufacturer. A web traverses the hollowed portion. A set screw extends through the web into the lever of the breaker, thereby securing the same to the web. The handle portion of the clip abuts against the face of the breaker, thus preventing rotation of the lever. The clip does not accept a lock and therefore would not appear to completely satisfy the OSHA regulations.
Another example of this class of lockout apparatus is a snap-on clip that sold as model BHLW by Bryant Electrical, Bridgeport, Conn., a division of Westinghouse Electric Corporation. This apparatus is a elongated generally C-shaped clip having cut-out regions respectively positioned to accept the operating lever of a breaker when the same is either in the "on" or the "off" position. The C-shaped clip snaps onto the housing of the breaker, with the lever projecting into one of the cut-outs therein. This clip is secured to the lever of a breaker with a set-screw.
In both of these last-mentioned examples of a lockout apparatus the securing mechanism the attaches the lockout apparatus to the breaker is not positively protected by a lock. Thus such apparatus are believed not capable of compliance with the OSHA regulations.
The third of the above-mentioned class of lockout apparatus has an integral switch with a removable operating handle. When assembled the handle is received in a correspondingly shaped recess provided in the switch. Insertion of the handle into the recess is essential before the equipment can be operated. Unless the shape of the handle and corresponding recess are unique or unusual such an apparatus is believed not capable of compliance with the OSHA regulations, inasmuch as a screwdriver or similar tool might disable the same.
In view of the foregoing it is believed advantageous to provide a lockout apparatus that prevents the use of an electrical device either by rendering the power plug incapable of insertion into an outlet and/or immobilizing the switching lever of a breaker. Further, it is believed advantageous to provide a lockout apparatus that is mechanically simple in construction and therefore economical to manufacture and use, yet at the same time accommodates a locking mechanism that must be positively removed before the electrical device may be used, thus rendering such a lockout apparatus able to comply with the OSHA regulations.